Messenger (problems) added

https://sudneela.github.io/posts/the-workings-of-whatsapps-end-to-end-encrypted-backups
https://www.ndss-symposium.org/ndss-paper/improving-signals-sealed-sender/
https://portswigger.net/daily-swig/multiple-encryption-flaws-uncovered-in-telegram-messaging-protocol
https://www.cryptofails.com/post/70546720222/telegrams-cryptanalysis-contest

Thanks @jermanuts
#1 (comment) & #1 (comment)

README.md

@@ -26,3 +26,5 @@
 * Docker - the [security nightmare](https://wonderfall.dev/docker-hardening/#is-it-really-a-security-nightmare) of [dependencies](https://wonderfall.dev/docker-hardening/#the-nightmare-of-dependencies)
 * SIM Card [Hijacking](https://www.maketecheasier.com/sim-card-hijacking/): How it works and what you can do about it
 * [SS7](https://secure-voice.com/ss7_attacks/) Attacks: Intercepting SMS and calls as easy as ABC
+* Messenger (problems): [Whatsapp's Backups](https://sudneela.github.io/posts/the-workings-of-whatsapps-end-to-end-encrypted-backups/), [Signal's Sealed Sender](https://www.ndss-symposium.org/ndss-paper/improving-signals-sealed-sender/), [Telegram](https://portswigger.net/daily-swig/multiple-encryption-flaws-uncovered-in-telegram-messaging-protocol)'s [*Cryptanalysis*](https://www.cryptofails.com/post/70546720222/telegrams-cryptanalysis-contest)
+